This invention relates generally to control interface devices, and more particularly to control interface devices for providing input to a computer system for manipulating an environment implemented by the computer system.
Control devices can be used for a variety of different control tasks. A user can conveniently select or operate different functions and features of a device using the control device. The control device preferably offers a more intuitive and easy-to-use way of interfacing with a device than using other inconvenient, bulky, or unintuitive controls.
Control devices can be implemented in a variety of forms. Those available control devices used for providing input to computer systems and other electronic apparatuses can take many forms. For example, when providing input to a graphical user interface implemented by a computer, such as to control a cursor, control devices such as mice and trackballs are often used. A mouse, however, has some disadvantages in that its operation requires a relatively large, flat workspace and the full use of a user's hand. This can be particularly disadvantageous for portable devices such as laptop computers. Trackballs do not require the large workspace of a mouse, but often are large, bulky devices that are not easy to integrate into the housing of a portable device.
Other control devices have also been developed for providing input to a computer system to control a cursor or otherwise manipulate a computer-implemented environment. One such device is a cylindrical, rotatable input device as described in U.S. Pat. Nos. 4,712,101; 4,724,715; and 4,823,634 of C. Culver which allows a user to accurately control a cursor with an intuitive and compact design. A cylinder is translated in one degree of freedom to provide input in one degree of freedom, e.g. to move a cursor horizontally. The cylinder is rotated about its lengthwise axis to provide input in a different degree of freedom, e.g. to move a cursor vertically. The cylinder can be simply pressed downward to provide the equivalent of a button press on a mouse. The use of such a cylindrical control has advantages over trackpads, since they tend to offer a more intuitive interaction for the user when manipulating a graphical object and also offer the possibility of providing force feedback to the user with actuators coupled to the cylinder, something which a trackpad cannot do.
A problem with control device designs such as the cylindrical control described above is that even the compact design of such devices can be too large for many portable devices. For example, the thinness of input devices has become a key criterion in portable computers and other mobile electronic equipment. The "trackpads" which sense finger position have become common on portable computers and are typically furnished in thicknesses of approximately 4 mm but can be reduced to a 2 mm thickness. The cylindrical controls described above, in contrast, are typically about 7 mm in diameter and can be reduced in size to approximately 5 mm. When cylinder diameter is reduced much below about 4 mm, operation begins to suffer as frictional fingertip coupling with the cylinder's surface is reduced. Some users complain that the control is difficult to engage.
A further problem with the cylindrical controls used in the prior art is that they are capable of controlling input for only two axes of motion or degrees of freedom. An additional problem is that these cylinder devices suffer from instability when designed for single-contact point-and-click operation. For example, downward pressure closes a switch connected to the cylinder, which performs a mouse-click operation. However, the instability causes unwanted "cursor creep" to occur, i.e. a small amount of rotation of the cylinder is caused when the cylinder is depressed, causing the cursor to move slightly in an undesired fashion.
There is therefore a need for cylinder control devices having a smaller thickness and greater stability to allow accurate input to a computer system or other device.